Process for drying yeast



E. KLEIN.

PROCESSFOR DRYING YEAST.

APPLICATION FILED MAR. 24, I922.

Patented June 20, 192 2.

2 SHEETS-SHEET I.

Jjiiarne/y.

E. KLEIN.

PROCESS FOR DRYING YEAST. APPLICATION FILED MAR. 24, 1922.

2 SHEETS-SHEET 2- E 5. By 9. F1 3;

M n/Z9 Patented June 20, 1922. I

. T all whom it may concern:

' chemical-engineer, a subject of the Kingdom of Roumania, residing at Voslau, near UNITED STATES PATENT. OFFICE,

ERWIN KLEIN, orivosnnu, NEAR VIENNA, nus'mm.

rnocnss r03 DRYING YEAST.

gene 20,1922.

Application filed March-25 1 922. Serial No. 546,502.

Be it known that I, Dr. ER'WI-N KLEIN,

Vienna, in the Republic of Austria, have invented new and useful Improvements in a Process for Drying Yeast, of which the fol lowing is a specification.

My invention relates to improvements in the manufacture of pressed yeast, especially to improvements in drying suclr yeast, and

consists of an improved method or process I for drying pressed yeast in order to insure a more uniformly dried final product which will be in a condition better adapted to be influenced and improved by added substances suitable to enhance the effect of such yeast, than the yeast obtained by the hitherto known drying processes.

The commonly known processes methods for drying pressed yeast consist in drying yeast by means of air passed through the particles of yeast which are obtained by dividing the 'yeast by means of'oscillating sieves, turning devices of different kinds. and other means so as to reduce the yeast into .a crumby or granulated mass. A still finer subdivision of the particles into a pulverized state hasnot been carried out in order .to avoid losses incurred bythe-flying away of the yeast in the form of dust together with the current of air. I

For conserving the energy of the yeast vduring the drying process, the temperature of the current ofiair employed for this pur- Eose is not allowed to surpassa certain limit.

enerally, this temperature of the current ofair used in connection with a crumby or granulated mass of yeast is not allowed to behigher than 10 to 15 degrees C: in the be ginning of thedrying process and may be raised to about 30 to 40 degrees. C. in the final .period thereof. The pressure ofsuch' air is about 3atmospheres.

According to the present invention the process for drying pressed yeast is carried out by means'ofa current of air ofhigher temperature and of lower pressure than hitherto employed on account of the yeast being brought into a inost finely divided state, preferably in a pulverized or dust-like state.

The fact that'the yeast isbrought into a and whereas with only coarsely divided yeast,

the pressure of the current of 'air must be 'materially above that of the atmosphere to penetrate into the interior of the relatively lar e particles of yeast and to dry them.

urthermore large quantities .of air of more elevated temperature may be passed through the yeast owing to its finely divided state on account of the dehydration of the yeast taking place so quickly that the particles of'the yeast are not heated to the temperature of the current of, air because they are cooled by the lomes of heatcreated by the evaporation of the content of water of the yeast particles.

The use of an elevated temperature of the current of air accelerates the dryin process and renders it more, economical. ontrary to the known processes in which the subdivision is only carried out to such degree that the yeast particles cannot fly away in the form of dust, the process according. to the invention is executed in such amanner brought thereby to a collector inwhich a finishingjof the of humidity is e ected by outlet ports and is supplied with acurrent of air of a temperature of about 20 to' 30 degrees and having a somewhat elevated pressure.' This current of'air, which may be dr ing to the desired content a ii means of'a still w more heated current of air.' 3 y carried out inthe yeast driedpreviously, is passed into the container and through-the yeast. contained therein until the degree of humidity .of'the yeast is lowered to about 30%. 3 The current of air is .then' heated to about 50 degrees C. and'regulated in such a manner that, the particles of yeast brought to the desired degree of hu-" midity are carried along and supplied to a special container serving to collect the dust? like particles of yeast. This; collector" may be provided with heating means thereby rendaring possible, if desired, a'final dryingof the yeast' 4 I Anapparatus suitable to carry out the process above described essentially consists of a container provided with conduits serving for the inlet and outlet of a current of air and. with an intermediate partition-bottom having apertures; the yeast is. deposited on this partition-bottom above which a device for. pulverizing' the yeast. is arranged. In order that the current of air may. come fromall sides into themost efiicient contact with.

' ferent-='size are deposited so that; a sorting ofthe yeastis thereby obtained. The compartments of the collector are each providedwith heating means, which may be independently regulated in order to finally dry, the yeast deposited therein-to the desired degree'and to obviate condensing of humidity.-- v i i In order: that my invention. may be roperly understood, I annex two sheets of drawin' sin which the preferred embodiment o -.my apparatus is illustrated.

'Fig.- ;1-1s a diagrammatical vertical secfltion through my improved drying device j together with the collector. Fig. 2-is a plan ofthe'intermediate partition bottom, con

si'stin i, in essence of two superposed plates "containing between themselves apertures .for the passage of air. 'In sector I of this figurejlthe lower v plate is illustrated, the upper f-plate beln' removed. ,Sector' II shows'theupper p ate aloneand sector III the plates in-super-position are illustrated.]F1gs. 3, iand- 5 are vertical-sections onthe lines a-a and b-- -b and 0-6,

respectively of the sectors I, II and III. onthe broken- Frg. Gris a vertical section lined-4020f Fig.2. R

'Thecontainer 'forthe reception of the yeasttoibe dried consists. of a'receptacle or basin .2 rotatable on its jmiddle axis and having.;ball-bearings 1;' abo've this reflfiptacle there is-arranged afixedcover 3 hermetically sealin'g'gthe receptacle by means of a liquid seal ;of known kind. I Axially "of thereceptacle a tube 5 extends-downwards into which discharges the conduit 6 forf the air, which has a concentric groove 7 filled with a liquid in which the tube 5"is-immersed.-in order to secure an'air-tight seal. The fixedcover is provided with'an outlet tube 8passing to 'the..- collector 9. A. pulverizing device is rotatably mounted in the depending-porformed in a screw-like manner. is further provided with scrapers or 'turners tion of the .fixed cover, and consists, in the illustrated example, of a plurality of cutterblades 10 fixed to. annular supports 11, 11

on the axis 12. These cutter-blades are arranged in a cylindrical surface and are The cover 13 extending from the lower side of the cover downwardsto an intermediate partition bottom 15 mounted in the receptacle 2 and having vertical apertures 14. These scrapers plough and-turn the yeast depositedon this bottom 15 when the receptacle is rotated.

The collector 9 consists of a plurality of concentric shafts 16, 17,18 enlarging conically on one end and discharging on the opposite ends into a series of compartments 19, 20, 21, respectively, each of which is provided with heating means, for example with steam-serpentines 19 20 and 21, re-

spectively. The shafts together with the compartments are included into a common which is provided. with doors (not shown for the removal of casing 22. This casin the collected and dried yeast from the compartments 19, 20, 21 which are alsoprovided with suitable doors (not shown), encloses also the upper conical endsv of the shafts and is provided at such upper portion with a heating device as indicated-at 23 for preventing rbndensation. Bathe-plates 24, 25

are fixed on the upper wall of the exterior shaft and extends into the conicahdischarge ends of the" other shafts. ,Air outlet ports 26 are arranged in the top plate ofthe cas ing, surmounted b a roof-like cover 27. The operation 0 the'device isjas follows:

The yeast to be dried is deposited through an opening (not shown) in. the cover 3 on the intermediate partition bottom 15 of the receptacle 2 which is then rotated by means j of a shaft 28 and of atoothed wheel-29;

mounted on this shaft and ,offa toothedi Wheel 30 provided at the outer circumferenceof the receptacle. The shaft'28 ijmay gbe' driven from any source of power. :The

shaft 28 simultaneously factuates, for ex ample by means of the. worm-gear 31, the shaft 12,'rotatably mounted in the cover so that the cutter-blades 10 fixed thereona're brought into rotation.

- By meansof-thefconduit 6 suitably preheated air is supplied and ispassed through the apertures'14 and through openings existdrying the same.

By the rotation of the receptacle -2-and of I ,the' intermediate partition :bottom 15 the yeast deposited thereon is partly lifted and which may. have the form-of rakes; simultaneously'the yeast is gradually cut intosmaller and smaller particles. cutters ing between the superposed plates and comes then into contact --w1th the yeast,'.thereby turned bythe fixed scrapers 13', the end of also act as-turning and distributing devices by partly turning, lifting and distributing the yeast.

- The air flows out through the conduit'8 to the collector 9 and carries with it such small particles of yeast, the drying and pulverizing of which has taken place to such an extent as to allow their being swept away by the current of air.

The particles of yeast carried away by the currentof air are deposited for the most part in the compartment 19, part of the yeast, namely the lighter particles, is lifted by the current. between the walls of the shafts 16 and 17 (as indicated in Fig. 1 by arrows),- is brought after passing the baflleplates 24 into the space between shaft 17 and 18 and fall down into the compartment20;

the still lighter particles are again lifted by 20 the current and arefinally deposited after passing the baffle-plate into. the compartment 21; v

- On account of the repeated change of the direction of the outflowing air caused by the 25 baffle-plates, the particles of yeast carried along with the air are separated in their totality from the air so that practically air without any'yeast-particles leaves the casing 22 through the openin 26. s

The collector there ore acts as a device\ I for separating the smallest dust-like par-l ticles of yeast from the current of air, so?

that losses are obviated. In order to free the walls of. the shafts from any particles '35 of yeast adhering thereto and to collect them,

7 in the respective compartment, a vibrator is provided consisting of a stem 32 actuated! by a. cam 33 etc the shaft 28 so, as to be pushed against the wall of the outer shaft- 16. -A .tension spring brings the stem-back '50 drying ofthe yeast it is necessary that the air comes into an' intimate contact with all sides of the yeast'particles. On account of the humidity the yeast tends to form lumps and to choke the openings for the passage of air thereby preventing a uniform contactof the'air with and an eflicient drying of the yeast. According to the invention theuniforrn contact of air under a low pressure with the'yeast is obtained by a special -shape of the intermediate partition bottom on which the yeast to be dried-is deposited. This bottom essentially consists of two superposed'plates 35, 37, which have therebetween a series of channels 39 in the shape 1 of dies, each series of 'channels being pro- 'vided in a sector of the plane, the lower and upper plate bein divided into a series of sectors. The sur ace of the lower plate consists in each sector of a series of bevelled ortapered planes 36, which are oblique and of which every two'adjacent planes form together roof-like surfaces. In each sector part of the upper plate 37 is removed so I that an opening 40 is created. One edge of the remalning part of the upper plate is zigzag-lined and preferably provided with teeth '38, whereas the other radial edge is unbroken. I

The form of the inclined or bevelled planes 3,6 of the lowerplate 35 is diagrammaticallyshown in sector I of 2, in which the section-lines of horizonta planes with the bevelled planes '36 of the lower plate are indicated by the zigzag'lines f-f, g.g, h-h. 7 as The lower'sides of the points of the teeth 38 rest on the lower plate 35 along lines' of the same level, i. e. along zigzag lines.' On account of the bevel of the planes of the lower plate the interstices 39 (Fig. 5) between these two plates, (the lower 35 and the upper plate 37) have thesha-pe of a die lying in the direction of concentric cycles. The discharge ends of these die-like channels 39 are divided by the teeth 38 of the upperplate 37 into a plurality'of separate discharge openings. The current of air sup plied by the conduit .6, passes through the vertical ports 13 .of the lower plate and enters the channels 39 between the lower and. v

upper plate, discharging in the yeastdeposited on the upper-plate. On account ofthe zigzag-form of the discharge end of the channels 39 a relatively large cross-section of dischargeis secured and the current is subdivided by the teeth 38 into single streams blowing in different directions. For I further subdividing and distributing the current of air the upper-plate 37 may be provided on its lower side with ribs resting I on the upper surface of the lower plate so that a series of channels or compartments of different directions are formedthrough which the air passes.

In order to prevent checking of the air inlets the die-like channels are situated in the direction of concentric cycles and pass obliquely from below to'above, thereby enabling removal of the yeast from the discharge openings when the-yeast is ploughed by the scrapers on rotating the receptac e 2.

To prevent escape of air between the edges of the rotating receptacle and the fixed cover the latter is provided with an annular 'plate A branch 43 of the air conduit 6 supplies 13d air into the annular space between the plate 42 and the sides of the receptacle and of the cover so that the same air pressure is created therein, thereby assisting the seal formed by the liquid.

What I claim as In invention and desire to secure by Letters atent is:

1. In the process of drying yeast, the steps which comprise simultaneously subjecting coarsely subdivided solid yeast masses to the action of a drying current of an innocuous gas and to such a pulverizing action that the particles of pulverized. yeast are eventually carried from the pulverization zone by; the said drying gas current, and,

thereafter, effecting separation of the yeast current.

3. In the process of drying yeast, the steps which comprise treating coarsely subdivided solid yeast masses with a drying current of an innocuous gas while the yeast is being reduced to such a state of subdivision that it is eventually taken up by the gas current, conducting the said gas current and the yeast carried thereby to a settling zone and permitting separation of the yeast from the gas current while further subjecting the yeast to temperature conditions which will efiect additional drying.

4. In the process of drying yeast, the steps which comprise treating coarsely subdivided solid yeast masses with a drying current of air while the yeast is being reduced to such a state of subdivision that it is eventually taken up by the air current, conducting the said air current and the yeast carried thereby to a settling zone and permitting separation of the yeast from the air current while further subjecting the yeast to temperature conditions which will effect additional drying 5. In the process of drying yeast, the steps which comprise simultaneously subjecting coarsely subdivided yeast masses to the action of a drying current of an innocuous gas and to such a pulverizing action that the particles .of pulverized yeast are carried from the pulverization zone by the gas current, separating the yeast from the gas cur.- rent and, during the entire process, maintaining the yeast and gas current at such a low temperature as not to destroy the vitality of the yeast.

' DR. E'RWIN KLEIN.

' Witnesses:

-CARL WUDENHUP, JOHANN Hose. 

